This invention relates to lock construction and particularly to a high security lock for use in a mortise lockset, padlock, tubular locks, rim locks, or other specialty locks. More particularly, this invention relates to the construction of a lock assembly to reduce its vulnerability to destructive physical attack.
A convention mortise-type lock assembly includes a threaded cylinder housing which screws directly into mortise lock case and an interchangeable key removable lock core of "FIG.-8" construction removably mounted within the cylinder housing. A conventional padlock assembly includes a padlock case formed to include a pair of bores for receiving a shackle and a single cavity of FIG. 8 cross-section for receiving an interchangeable lock core.
A conventional lock cylinder assembly further includes a cylinder ring positioned on the lock cylinder housing to surround an exposed portion thereof to protect the lock cylinder housing and interchangeable core from attack. It is known to form a cylinder cap to include a hole alignable with the key plug in the lock cylinder housing to permit a user to insert a key into the key slot of the key plug through the aligned hole when a protective cylinder cap is used in a lockset. An assembly for a padlock is known to include a security harness of sturdy construction that is designed to enshroud the exterior of the padlock case to protect the interchangeable padlock core from destructive physical attack.
Notwithstanding the foregoing known lock features, the security of conventional locks can be violated in may different ways. Several lock-breaking techniques are explained in the following paragraphs. The improved lock of the present invention is specifically constructed to include several advantageous features which cooperate to frustrate the efforts of a lock-attacker who attempts to break the security of the improved lock and which simplify the construction and assembly of cylinder locks and padlocks. An object of the present invention is to provide a lock that will resist being opened by the application of a rotary force with tools: in the key slot, on the exposed part of a cylinder, or on the exposed portions of the lock assembly.
According to the present invention, a lock comprises a lock housing, and an interchangeabe core including a core body, a core sleeve, and a key plug having a key slot. A cap is mounted on the lock housing to protect the core, and a key-way disc is mounted in the cap to protect the key plug while still permitting insertion of an operating or control key into the key slot of the key plug.
The key-way disc includes a secondary key slot for alignment with the primary key slot of the key plug. The cap includes a disc-receiving passageway extending between an outer face and the inner face for alignment with the key plug. The cylinder cap includes a radially inwardly projecting lip in the passageway. The key-way disc includes a cylindrical member having an exterior cylindrical wall and a flange for engaging the cap lip to position the key-way disc in the disc-receiving passageway. The key slot of the cylindrical member opens radially outwardly through the exterior cylindrical wall of the disc. The flange includes a rib member extending radially outwardly from the exterior cylindrical wall of the cylinder portion, and a bridge member integrally coupled to the rib member. The bridge member covers a portion of the key slot opening in the cylinder member's exterior wall and is protectively captured intermediate the lip of the cap and an outer face of the lock core.
According to one preferred embodiment of the present invention, the cap is used with a lock cylinder and includes an inner face and a pin-receiving recess in the inner face. The cylinder cap is securely retained in a non-rotatable position on the lock cylinder housing due to the provision of a rotation-blocking means which is situated intermediate the cap and the lock cylinder housing. The cylinder cap is threadedly mounted on the lock cylinder housing to position the inner face of the cap in closely-confronting relation to an outer face of the lock cylinder housing to cause the pin-receiving recess to open toward the outer face of the lock cylinder housing. The lock cylinder housing includes a longitudinal bore having an opening in the outer face of the lock cylinder housing. A freely rotatable blocking pin is received in the bore. The spin-free blocking pin is extendable through the bore opening to engage the recess in the inner face of the cylinder cap. A setscrew is threadedly received in the lock cylinder housing bore and extendable therein to urge the spin-free blocking pin toward its engaged position in the cylinder cap. Thus, the setscrew of the present invention is protected by a free-spinning pin and is not susceptible to an attack of the type in which the setscrew is intercepted by a drill bit and rotated back into the lock cylinder housing land out of the threaded engagement with a protective cylinder cap. A cylinder ring having a drill-resistant circumferential groove is installable on the cylinder housing to protectively surround the cylinder cap.
According to another embodiment of the present invention, the cap is used with a lock cylinder and includes a cavity for receiving a forward portion of the core body and flange means for engaging the core body to position the cylinder cap in closely-confronting relation to an outer face of the lock cylinder housing when the interchangeable lock core is received in the lock cylinder housing. An upper lobe of the core body is formed to include a pair of lug-receiving slots. Each slot has an opening in an exterior surface of the upper lobe. The flange means includes a pair of lugs for engaging the slots in upper lobe of the core body. In this embodiment, the cylinder cap is conveniently removable from its cylinder-protecting position by means of the "control" key for the lock since the cylinder cap is carried on the core body of the interchangeable core and the core is itself removable from the lock cylinder by means of said "control" key. A cylinder ring having a drill-resistant circumferential groove is installable on the cylinder housing to protectively surround the cylinder cap.
According to yet another embodiment of the present invention, the cap is used with a padlock and includes a cavity for receiving a forward portion of the core body and flange means for engaging the core body to position an inner face of the padlock cap in communication with a core-receiving chamber formed in the padlock to protectively block at least a portion of the chamber opening and thereby provide a padlock security shield to protect a padlock core from being pulled, drilled, chiseled, or damaged using other methods during an attack. An upper lobe of the core body is formed to include a pair of lug-receiving slots. Each slot has an opening in the exterior surface of the upper lobe. The flange means includes a pair of lugs for engaging the slots in the upper lobe of the core body. In this embodiment, the padlock cap is removable from its recessed core-protecting position within the padlock case by means of the control key for the lock since the padlock cap is carried on the core body of the interchangeable core and the core is itself removable from the padlock case by means of said control key.
One feature of the present invention is the provision of spin-free means for blocking rotation of the protective cylinder cap in relation to the lock cylinder housing to prevent exposure of the lock core to attack. The spin-free means includes a setscrew and a freely rotatable blocking pin received in the longitudinal bore of the lock cylinder housing. The spin-free blocking pin advantageously prevents rotation and removal of the cylinder cap from its protective position on the lock cylinder housing by providing a blocking member that is not itself rotatably disengagable from the cylinder cap. In the absence of the novel freely rotatable blocking pin, destruction of a lone setscrew in threaded engagement with both the lock cylinder housing and the cylinder cap would be an easy task. Such destruction could be easily accomplished by drilling the forwardly presented face of the cylinder cap in the proper location to cause the drill bit to intercept the lone setscrew. The drill could then be operated to "back" the setscrew out of threaded engagement with the cylinder cap. Once the lone setscrew is disengaged from the cylinder cap, the lock-attacker could easily remove the protective cap and violate the security of the lock by picking or by the application of force. A lock-attacker seeking to violate the security of the improved lock of the present invention will soon learn that it is not possible to drill the face of the cylinder cap to intercept and rotatably "back" a lone setscrew from rotation-blocking engagement with the protective cylinder cap. Instead, the attack drill bit will intercept and rotate only the novel freely rotatable blocking pin. Thus, the setscrew of the present invention is insulated from attack since it only urges the spin-free blocking pin into engagement with the cap and does not threadably engage the protective cylinder cap.
Another feature of the present invention is the provision of a cylinder cap including flange means for engaging the lock core body to position the cylinder cap in closely-confronting relation to an outer face of the lock cylinder housing when the interchangeable lock core is received in the housing. This feature advantageously permits key removal of the cylinder cap to expedite disassembly of the lock for core replacement or recombination. In addition, this feature advantageously blocks rotation of the cylinder cap in respect to the lock cylinder housing during an attack.
Yet another feature of the present invention is the provision of a padlock cap including flange means for engaging the lock core body to position the cap in a recess in the padlock case to protect the interchangeable lock core body while it is received in its chamber in the padlock case. This feature advantageously permits key removal of the cap in a padlock environment to expedite disassembly of the lock for core replacement or recombination. Further, the placement of the padlock cap in a recess formed in the padlock case protects the core from being pulled with a "slam-puller," a "nose-puller," or other similar lock attack tool.
Still another feature of the present invention is the provision of a free-wheeling key-way disc to improve the pick-resistance and drill-resistance of a lock. The key-way disc provides an additional obstacle a lock-attacker must overcome during an attempt to pick the lock by hanging the segment pins on either the "operating" or "control" shearline. It is more difficult to insert a tension device into the key slot of a key plug when the key-way disc of the present invention is installed in a cylinder cap. Further, the key-way disc provides a barrier to prevent someone from drilling into the key plug.
Another feature of the present invention is the provision of a bridge member on the flange of the key-way disc. The bridge member is substantially inaccessible and hidden from view under a lip formed on the cap to prevent a lock-attacker from breaking the exposed part of the key-way disc with a chisel, collapsing the disc together about its key slot, and prying the disc out of the passage in the cap to gain access to the key plug.
Yet another feature is the provision of a cylinder ring having a groove in an interior wall that opens toward either the cylinder cap or the lock cylinder. Illustratively, the cylinder ring is formed to include a circumferential V-shaped groove that is heat-treated to provide a pair of heat-treated drill-resistant surfaces positioned to pose a pair of significant drill-thwarting obstacles during an attack on the cylinder ring. The cylinder ring is hardened so that it has a very hard outer surface and yet is not brittle and easily broken. The walls of the circumferential groove are hardened and provide a significant barrier to drilled attack. The security of a conventional cylinder lock can also be violated by destroying the cylinder ring to expose the cylinder and core to attack. This is often accomplished by drilling one or more holes into the forwardly presented face of the cylinder ring, splitting the ring along the drilled hole with a chisel, and driving a wedge into the split to break the cylinder ring apart. The drilled hole creates a stress riser in the conventional cylinder ring to permit a lock attacker to more easily crack through the ring with a chisel. The hardened groove walls of the improved cylinder ring cooperate to intercept and break a drill bit being used to drill a hole in the hardened forwardly presented face of the cylinder ring for the illicit purpose of creating a stress riser therein to more easily split and crack the cylinder ring.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.